The present invention relates to a slide valve, in particular to a slide valve for use in vacuum apparatuses, and including a housing having a flow channel, a slide plate located in the housing and displaceable transversely to a flow channel axis between a closed position, in which it blocks flow through the flow channel, and an open position, in which it provides for the flow through the flow channel, and a seal ring surrounding the flow channel and engaging the slide plate in its closed position and disengageable from the slide plate in its open position.
The slide valve of the above-described type are well known. A slide valve disclosed in German patent No. 1,264,191 has a seal ring formed of an elastomeric material and located in an annular groove, the height of which measured in an axial direction of the flow channel is larger than the seal ring diameter. A pressure medium is supplied into the annular grove so that, when the slide plate is displaced into its closed position, the pressure medium acts on the seal ring and biases it against the slide plate. In a slide valve of this type, disclosed in a German publication DE-OS 34 47 008, metal bellows are provided on opposite sides of the slide plate, when the slide plate is in its closed position, which bellows carry seal rings on sides thereof adjacent to the slide plate, respectively. These metal bellows, which are arranged in pairs and circumscribe respective flow channels, are subjected to the action of a pressure medium and bias the seal rings against the slide plate when the latter is displaced into its closed position. Inside of the metal bellows, there are provided tension springs which lift the seal rings off the slide plate when the metal bellows are not subjected to fluid pressure. A similar construction is disclosed in U.S. Pat. No. 3,145,969.
Finally, German utility model DE-GM 77 31 993 discloses a slide valve in which the seal ring is formed as an annular piston, displaceable in an annular groove provided in the slide valve housing, and opposite sides of which are subjected to the action of a pressure medium.
All of the described constructions of a slide valve are very expensive and, in addition, their flow channel region is accessible with much difficulties so that the slide valve should be completely disassembled for, e.g., rinsing purposes. And this is possibly only when the slide valve is completely removed from the apparatus in which it is mounted.
The operational processes which take place in vacuum apparatuses, in which such slide valve are generally used, do not permit contamination of the flow region of the slide valve, so that it should be possible to clean, from time to time, the inside of the slide valve, in particular, the parts which are directly used for sealing purposes.
Accordingly, the object of the invention is a slide valve of the above-described type having a construction which would permit its rinsing, without taking the entire slide valve from the apparatus in which it is mounted.
Another object of the invention is a slide valve of the above-described type which would insure easy access to the rinsable parts which should be easily removable.